Effect of matrix dislocation strengthening on deformation-induced martensitic transformation behavior of metastable high-entropy alloys

In this study, we investigate the influence of dislocation strengthening in the metastable parent phase on the deformation-induced martensitic transformation behavior of a face-centered cubic (fcc) Co20Cr20Fe34Mn20Ni6 high-entropy alloy. Annealed and hot-swaged specimens were prepared. In-situ neutron diffraction experiments captured an accelerated transformation kinetics in the hot-swaged specimen due to accumulated dislocations. The phase-specific macrostress development showed that the hexagonal close-packed epsilon-martensite predominantly accommodated the macroscopic plastic deformation of the annealed counterpart. Conversely, the matrix dislocation strengthening promoted cooperative plasticity of the gamma-matrix and the epsilon-martensitic phase, thus enhancing yield stress while preserving ductility.